Glass break detector OK on same wall of protected window ?


Old 11-23-15, 08:36 AM
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Cool Glass break detector OK on same wall of protected window ?

Hi , I have a quick one.

On some installation , they ask to put the detector on adjescent or opposite wall of the window.

Is it OK to put the detector on the same wall ?
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Old 11-23-15, 09:54 AM
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Can you? Yes. Should you? No! A glassbreak detector is a tool, with instructions. Use any tool contrary to its instructions, it may not work as intended.

I don't think that is what you want.
Old 11-23-15, 10:41 AM
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First, it always helps if you give specific brand names and model numbers of equipment you ask about. Glass break sensors use a variety of different technologies, and the optimum deployment varies with make and model.

If the instructions that came with your sensor says it should be mounted on an adjacent or opposite wall, then those are the optimum places to put it. It's probably a purely acoustic sensor, and will "hear" best when not on the same wall, the same way you hear best when sound sources are in front of or beside you and sound waves are funneled by your ears.

It may still work on the same wall as the window, but will be more susceptible to sounds from outside the window, whose waves are hitting the other side of that wall. Sound from the window breaking will be hitting the sensor microphone at an extremely oblique angle, edge-on, which means much less sound actually hitting the mike. Depending on the sensor's distances from the window, adjacent wall, opposite wall, and the size of the room, it may collect more sound from the echoes than the window itself. So the room size is a consideration. Your instructions should name a maximum coverage distance--figure that distance as the distance sound actually has to travel to hit the sensor's microphone (which will be aimed out from the sensor's face) at a decent angle, not edge-on as it would on the same wall.

All that said, it may work fine. The only way to be sure is to try it. Keep in mind that "trying it" means waiting over a period of weeks to see if it false-alarms.

If you live in an environment with occasional loud sounds outside your window, the sensor may be more susceptible to false alarms. A good quality sensor will filter out anything that doesn't resemble breaking glass--hopefully you're not using any of the cheap Chinese junk you find on eBay.

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